Lead inhibition of Mg/sup 2 +/-ATP-dependent calcium transport in rat liver plasma membranes
In every tissue in which lead/calcium interactions have been examined, lead interferes with cellular calcium homeostasis resulting in an apparent increase in cellular calcium and alterations in calcium-mediated processes. The mechanism(s) by which lead increases cellular calcium are unknown. This study examines the effect of lead (5 nM to 50 ..mu..M) on Mg/sup 2 +/-ATP-dependent calcium transport activity in rat liver plasma membranes. Plasma membrane vesicles were prepared by Percoll density gradient centrifugation. This preparation shows a Mg/sup 2 +/-ATP-dependent calcium uptake with an initial rate of 5 nmol/mg protein/min and reaches a total equilibrium accumulation of 33 nmol/mg protein within 20 min at 20 ..mu..M CaCl/sub 2/, 1 mM ATP, 5 mM MgCl/sub 2/, 100 mM KCl, 5 mM azide, 30 mM histidine-imidazole, pH 6.8. Under these conditions lead inhibits calcium accumulation with half maximal inhibition at 1 ..mu..M; yet even at 50 nM lead, significant inhibition is observed. These observations indicate that lead impairs plasma membrane Ca/sup 2 +/ transport. As a result cellular calcium homeostatis is perturbed. This may represent an important mechanism in the expression of lead toxicity.
- Research Organization:
- Albert Einstein College of Medicine, Bronx, NY
- OSTI ID:
- 5494033
- Report Number(s):
- CONF-8604222-
- Journal Information:
- Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States), Vol. 45:3; Conference: 70. annual meeting of the Federation of American Society for Experimental Biology, St. Louis, MO, USA, 13 Apr 1986
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CALCIUM
HOMEOSTASIS
MEMBRANE TRANSPORT
LEAD
TOXICITY
ATP
CATIONS
CELL MEMBRANES
INHIBITION
LIVER
MAGNESIUM COMPOUNDS
RATS
ALKALINE EARTH METAL COMPOUNDS
ALKALINE EARTH METALS
ANIMALS
BODY
CELL CONSTITUENTS
CHARGED PARTICLES
DIGESTIVE SYSTEM
ELEMENTS
GLANDS
IONS
MAMMALS
MEMBRANES
METALS
NUCLEOTIDES
ORGANIC COMPOUNDS
ORGANS
RODENTS
VERTEBRATES
560301* - Chemicals Metabolism & Toxicology- Cells- (-1987)